Platinum-tin catalyst regeneration

ABSTRACT

Hydroconversion of hydrocarbons, particularly reforming of naphthas, is conducted in the presence of hydrogen with a catalyst comprising a platinum group component in an amount of from 0.01 to 5 weight percent, a tin component in an amount of from 0.01 to 5 weight percent and a halogen in an amount of from 0.1 to 3 weight percent in association with a porous solid carrier.

United States Patent 1191 1111 3,875,049 Kluksdahl *Apr. 1, 1975 [5PLATINUM-TIN CATALYST 3.531.543 9/1970 Clippinger et al. 260/6833REGENERATION glippinger et al. ox n e Harris Kluksdahl, San Rafael.3,700,588 10/1972 Weisang et al. 208/139 Cahf. 3,725,304 4/l973 Wilhelm208/l39 3,740,328 6/l973 Rausch 208/139 [73] Asslgnee: 'f'" Cmnlmy,3,745,112 7/1973 Rausch 208/139 Francisco, callf- 3,764,557 10/1973Kluksdahl 208/139 [*1 Notice: The portion of the term of Hayes patentsubsequent to Oct. 9, 1990, D has been disdaimed Prunary E.\'am1r1erDelbert E. Gantz Amman: Examiner-James W. Hellwege Filed: P 1 1973Attorney, Agent, or Firm-G. F. Magdeburger; R. H. [211 App]. No: 355,607Dav1es; .l. J. De Young Related US. Application Data 57 ABSTRACT co 9 18 1 [970, bwhich Hydroconversion of hydrocarbons particularly reg; 'g 08659)! formlng of naphthas, is conducted 1n the presence of a an onehydrogen with a catalyst comprising a platinum group component in anamount of from 0.0l to 5 weight per- [52] Cl 547 472 cent, a tincomponent in an amount of from 0.01 to 5 l Cl 6 "/14 weight percent anda halogen in an amount of from g i 140 0.1 to 3 weight percent inassociation with a porous 252/441, 442, 466 PT, 416 mm came [56]References Cited 4 Claims, 6 Drawing Figures C LIQUID PRODUCT, VOL.AVERAGE CATALYST TEMPERATURE, F

PATEIIIED 3. 875.049

SHEET 1 [IF 2 96o PLATINUM CATALYST 900 PLATINUM TIN CATALYST I l I I II l l l I I I O 5 IO I5 3O 4O 5O HOURS ON STREAM FIG. I

[PLATINUM TIN CATALYST 86 82 PLATINUM CATALYST 7 I l 1 1 1 l l O 5 IO I520 25 3O 35 4O 45 5O 55 60 HOURS ON STREAM FIG. 2

INVENTOR HARRIS E. KLUKSDAHL L ATTORNEYS 1 PLATINUM-TIN CATALYSTREGENERATION CROSS REFERENCE This is continuaton, of application Ser.No. 8,663. filed Feb. 4, I970 which is a continuation-in-part ofcopending application Ser. No. 865,010 filed Oct. 9, 1969, nowabandoned.

BACKGROUND OF THE INVENTION l. Field The present invention is directedto hydrocarbon hydroconversion processes, and more particularly toreforming processes. Still more particularly, the present invention isconcerned with a catalytic composition and a process for thehydroconversion of hydrocarbon in the presence of the catalyticcomposition. The catalyst comprises a platinum group component and a tincomponent in accociation with a porous solid carrier.

2. Prior Art Hydrocarbon hydroconversion processes, such ashydrocracking, hydrogenation, hydrofining, isomerization, alkylation,desulfurization and reforming, are of special importance in thepetroleum industry as a means for improving the quality and usefulnessof hydrocarbons. The requirement for a diversity of hydro carbonproducts, including, for example, high quality gasoline, has led to thedevelopment of many catalysts and procedures for converting hydrocarbonsin the presence of hydrogen to useful products. A particularly importanthydrocarbon hydroconversion process is reforming. Although many featuresof the present invention are discussed in terms of reforming, it is tobe understood that the present invention relates to other bydrocarbonhydroconversion processes as well.

In the development of catalysts for catalytic hydroconversion processes,it is important that the catalyst exhibit not only the capability toinitially perform the specified functions but also that it has thecapability to perform satisfactorily for prolonged periods of time.Thus, in the development of new catalysts, attention must be directed tothe activity, selectivity and stability characteristics of the catalyst.The activity of a catalyst is a measure of the catalysts ability toconvert hydrocarbon reactants to products at a specified severity level,i.e., at a particular temperature, pressure. hydrogen to hydrocarbonmole ratio, etc. The selectivity of the catalyst refers to the abilityof the catalyst to produce high yields of desirable products, andaccordingly low yields of undesirable products. The stability of acatalyst is a measure of the ability of the catalyst to maintain theactivity and selectivity characteristics over a specified period oftime. Thus, for example, a catalyst for successful reforming mustpossess good selectivity, i.e., be able to produce high yields of highoctane number gasoline products and accordingly low yields of lighthydrocarbon gases. The catalyst should also possess good activity inorder that the temperature required to produce a certain quality productneed not be too high. Also, the stability should be such that theactivity and selectivity characteristics can be retained duringprolonged periods of reforming operation. Thus, the temperaturestability, which is generally measured as the fouling rate of thecatalyst, should be such that the temperature need not be raised at anexcessively high rate in order to maintain conversion of the feed to aconstant octane product. Also, the yield stability of the catalystshould be such that the production of valuable C gasoline products doesnot decrease appreciably during prolonged operation at a constantconversion.

As indicated above, the present invention is particularly concerned withcatalytic reforming, that is, the treatment of naphtha fractions orfeeds to improve the octane rating. Most catalytic reforming operationsare characterized by employing catalysts comprisingdehydrogenation-promoting metal components associated with porous solidcarriers, which catalysts selectively promote such hydrocarbon reactionsas dehydrogenation of naphthenes to aromatics, dehydrocyclization ofparaffms to naphthenes and aromatics, isomerization of normal paraffinsto isoparaffins, and hydrocracking of relatively long-chained paraffins.Most catalysts used in reforming processes comprise platinum groupcomponents, particularly platinum, in association with porous solidcarriers, for example, alumina. Research efforts have been expended toseek substitutes for platinum and/or to seek catalytic promoters to usewith platinum catalysts to increase their activity, stability. andselectivity characteristics.

SUMMARY OF THE INVENTION In accordance with the present invention, animproved hydroconversion process can be conducted in the presence of acatalyst comprising a platinum group component, a tin component, and ahalogen associated with a porous solid carrier. The platinum groupcomponent is present in an amount of from 0.01 to 5 weight percent basedon the finished catalyst; preferably the platinum group component isplatinum. Preferably the tin component is present in an amount of from0.01 to 5 weight percent and the halogen in an amount of from 0.l to 3weight percent, based on the finished catalyst. The hydrocarbonhydroconversion process is preferably the reforming of naphtha orgasoline fractions to produce high octane products.

Also, in accordance with the present invention, a novel catalyticcomposition of matter has been discovered comprising a porous solidcarrier, preferably a porous inorganic oxide carrier, having associatedtherewith from 0.0] to 5 weight percent of a platinum group component,0.01 to 5 weight percent of a tin component, and 0.] to 3 weight percentofa halogen. The catalytic composition is preferably in a reduced state.The novel catalyst of the present invention is found to be highly activeand stable for the reforming of naphtha and gasoline boiling rangehydrocarbons and, in fact, is superior to commercial reforming catalystscontaining only a platinum group component.

Another of the several advantages of the present invention is that thecatalyst does not require presulfldin g to reduce initial formation oflow molecular weight hydrocarbons during startup of the reformingprocess, in contrast to other reforming catalysts which often re quiresuch pretreatment for such purpose.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention may be betterunderstood and will be further explained hereinafter by reference to theFigures.

The graphs in FIGS. 1 and 2 show for comparison purposes data fromsimulated life tests indicating the reforming activity and stability ofa conventional catalyst comprising platinum and chloride on an aluminasupport and a catalyst comprising platinum, tin, and chloride on analumina support. Conditions of opera tion were more severe than normallyused in reforming operations in order to simulate the response of thecatalysts to much longer tests (life tests). The graph in FIG. 1 showsthe average catalyst temperature as a function of the length ofthe testor hours onstream re quired to maintain a 99 F-l clear octane for eachof the two catalysts. The graph in FIG. 2 shows as a function of thetime onstream the yield of C,-,+ liquid product or gasoline having 99 Flclear octane rating produced during the reforming of each of the twocatalysts. From FIG. 2 it is seen that the process using theplatinum-tin catalyst yields significantly higher amounts of 99 F] clearoctane product than the process using the plati num catalyst withouttin.

The graphs in FIGS. 3 and 4 show, as a function of the onstream time,the average catalyst temperature and the C gasoline yield produced,respectively, for an accelerated test (as defined in Example 2)reforming process conducted in accordance with the present inventionusing a freshly prepared platinum-tin chloride catalyst. The graphs inFIGS. 5 and 6 show the same information using a catalyst that wasregenerated and activated as later described after being used in a pilotplant test. The reforming conditions included an average reactorpressure of 125 psig, a hydrogen-tohydrocarbon molar ratio of 3. and aliquid hourly space velocity of 3. The catalyst temperature was adjustedas fouling occurred to maintain production of a I F-l clear octaneproduct. The catalyst responded well to regeneration and the yield of Cproduct remained high over the entire run length. Furthermore, thereforming periods, both with fresh and regenerated and activatedcatalyst, were of substantial duration, i.e., around to hours. This issignificant considering the low pressure and accelerated nature of thetests.

DESCRIPTION OF THE INVENTION The porous solid carrier or support whichis employed in the preparation of the catalyst of the present inventioncan be any of a large number of materials upon which catalyticallyactive amounts of a platinum group component, a tin component, and ahalogen component can be included. The porous solid carrier can be, forexample, charcoal, or carbon. preferably, the porous solid carrier is aninorganic oxide. A high surface area inorganic oxide carrier isparticularly preferred, e.g., an inorganic oxide having a surface areaof greater than 50 m /gm and preferably greater than about 150 m lgm.Generally, the porous inorganic oxides which are useful as catalystsupports for the present invention have surface areas of from about 50to 750 m lgm. Natural or syhthetically produced inorganic oxides orcombinations thereof can be used. Typical acidic inorganic oxidesupports which can be used are the naturally occurring aluminumsilicates, particularly when acid treated to increase the activity, andthe synthetically produced cracking supports, such as silica-alumina,silica-zirconia, silica-alumina-zirconia, silica-magnesia,silica-alumina-magnesia, and crystalline zeolitic aluminosilieates. Forhydrocracking processes it is generally preferred that the carriercomprises a siliceous oxide. Generally, preferred hydrocrackingcatalysts contain silica-alumina, particularly silica-alumina having asilica content in the range of to 99 weight percent.

For reforming processes, it is generally preferred that the catalyst haslow cracking activity, that is, has limited acidity. It is preferred forreforming processes to use inorganic oxide carriers such as magnesia andalumina. Alumina is particularly preferred for purposes of thisinvention. Any of the forms of alumina suitable as a support forreforming catalysts can be used, e.g., gamma alumina, eta alumina, etc.Gamma alumina is particularly preferred. Furthermore, alumina can beprepared by a variety of methods satisfactory for the purposes of thisinvention. Thus, the alumina may be prepared by adding a suitablealkaline agent such as ammonium hydroxide to a salt of aluminum, such asaluminum chloride, aluminum nitrate, etc., in an amount to form aluminumhydroxide which on drying and calcining is converted to alumina. Aluminamay also be prepared by the reaction of sodium aluminate with a suitablereagent to cause precipitation thereof with the resulting formation ofaluminum hydroxide gel. Also alumina may be prepared by the reaction ofmetallic aluminum with hydrochloric acid, acetic acid, etc., in order toform a hydrosol which can be gelled with a suitable precipitating agent,such as ammonium hydroxide, followed by drying and calcination.

The catalyst of the present invention comprises a platinum groupcomponent, a tin component, and a halogen in association with a poroussolid carrier, particularly a porous inorganic oxide carrier. Theplatinum group component should be present in an amount of from 0.01 to5 weight percent, preferably from 0.01 to 3 weight percent, based on thefinished catalyst. The platinum group component embraces all the membersof Group VIII of the Periodic Table having an atomic weight greater than100, i.e., ruthenium, rhodium, palladium, osmium, iridium, and platinum,as well as compounds and mixtures of any of these. Thus, the platinumgroup components are the Group VIII noble metals or compounds thereof.Platinum is preferred because of its better performance in reforming andother hydroconversion reactions. When platinum is used, particularly inreforming processes, the preferred amount is from 0.01 to 3, morepreferably 0.1 to 2 weight percent, and still more preferably 0.] to 0.9weight percent. Regardless of the form in which the platinum groupcomponent exists on the carrier, whether as metal or compound, e.g., asan oxide, halide, sulfide, or the like, the weight percent is calculatedas the metal. Reference to platinum," platinum group component," etc.,is meant to refer to both the metal and the compound form.

The tin component is present on the catalyst in an amount of from 0.01to 5 weight percent and preferably from 0.01 to 3 weight percent andmore preferably from 0.l to 1.5 weight percent, based on the finishedcatalyst. The tin component can exist on the carrier in the metallicform or as a compound, e.g., as an oxide, sulfide, or the like.Reference to tin" is meant to refer to both the metal and the compoundform of tin. Regardless of the form in which tin exists on the carrier,whether as the metal or compound form, the weight percent is calculatedas the metal.

The platinum group component and tin component can be intimatelyassociated with the porous solid car rier by suitable techniques such asion exchange, precipitation, coprecipitation, etc. Preferably, however,the components are associated with the porous solid carrier byimpregnation. Furthermore, one of the components can be associated withthe carrier by one procedure, e.g., ion exchange, and the othercomponent associated with the carrier by another procedure, e.g.,impregnation. As indicated, however, the components are preferablyassociated with the carrier by impregna tion The catalyst can beprepared by either coimpregnation of the platinum group component andtin component or by sequential impregnation.

The platinum group component is preferably associated with the poroussolid carrier by impregnation of water soluble compounds of the platinumgroup metals. For example, platinum may be added to the support byimpregnation from an aqueous solution of chloroplatinic acid. Otherwater soluble compounds of platinum which may be incorporated as part ofthe impregnation solution are, for example, ammonium chloroplatinates,platinum chloride, polyammine platinum salts, etc. Compounds of theother platinum group components may be used as, for example, palladiumchloride, rhodium chloride, etc. lmpregnation solutions using organicsolvents may also be used.

The tin component is preferably associated with the porous solid carriersuitably by impregnation. impregnation can be accomplished using anaqueous solution of a suitable compound. However, when using an aqueoustin impregnating procedure, the resulting catalytic composition ofmatter is preferably activated in order to obtain optimum catalyticactivity. The preferred activation process comprises reacting thecatalytic composition with an activating gas including oxygen at atemperature from 500F. to 1300F. for at least 0.5 hours to calcine it. Ahalogenating component, for example, carbon tetrachloride, chloroform,t-butyl chloride, t-butyl fluoride or the like, may preferably be addedduring the activation. The activating gas may be slightly moist. The useof a slightly moist activating gas is preferred if a halogenatingcomponent is included with said activating gas.

As another embodiment, the tin component is impregnated on the carrier,which has previously been im pregnated with a decomposable compound of aplati' num group component and calcined, from an organic solution. Thus,a tin compound dissolved in ether or alcohol or other suitable organicsolvent may be used as the impregnation solution. Care should beexercised after impregnation that the organic material is completelyevaporated or removed from the catalyst prior to heating of the catalystin the presence of a reducing atmosphere, for example, hydrogen. Thus,careful drying or calcination should follow impregnation using anorganic solvent in order to thoroughly rid the catalyst of hydrocarbonmolecules. The presence of hydrocarbons on the catalyst during contactwith a hydrogen atmosphere appears to detrimentally affect theperformance of the catalyst during hydroconversion reactions as, forexample, reforming. The organic solution is preferably substantiallyanhydrous. If it is not substantially anhydrous, then the catalyticcomposition should preferably be activated as described above to insurethat it has substantially optimum activity. In general, if the catalyticcomposition is contacted with a substantial amount of moisture during orafter impregnation with a tin component, it is desirable to activate thecomposite as disclosed above to insure that it has substantially optimumactivity.

Suitable tin compounds which can be used for impregnation are thechlorides, nitrates, sulfates, acetates and ammine complexes. Also,useful tin compounds include the organic tin compounds, such as thetetraalkyl compounds (tetra, butyl, phenyl, ethyl, propyl, octyl, decyl,tin and the like), and the tetra-alkoxide compounds (tin tetraethoxides,etc.). Other useful compounds are the stannates. The particular compoundchosen will depend somewhat on the solvent chosen, whether water, or anorganic solvent. The tin can be in the stannous or stannic oxidationstate. It is particularly preferred to use the chloride or halidecompounds of tin inasmuch as the impregnation not only distributes thetin component but also the halide component, which is beneficial to mosthydroconver' sion reactions.

it is necessary to promote the catalyst for hydrocar bon hydroconversionreactions by the addition of com bined halogens (halides), particularlyfluorine or chlorine. Bromine may also be used. The catalyst promotedwith halogen usually contains from 0.] to 10 weight percent, preferably0.1 to 3 weight percent, total halogen content. When the halogen ischlorine, it even more preferably contains 0.5 to 2.0 weight percent andstill more preferably 0.8 to 1.6 weight percent, total chlorine content.The preferred amounts are particularly desirable in reforming. Thehalogens may be incorporated onto the catalyst at any suitable stage ofcatalyst manufacture, e.g., prior to or following incorporation of theplatinum group component and tin component. Generally, the halogens canbe combined with the catalyst by contacting suitable compounds such ashydrogen fluoride, ammonium fluoride, hydrogen chloride, and ammoniumchloride, either in the gaseous form or in the water soluble form withthe catalyst. Preferably the fluorine or chlorine is incorporated withthe catalyst from an aqueous solution containing the halogen. Oftenhalogen is incorporated with the catalyst by impregnating with asolution of a halogen compound of a platinum group metal or tin. Thus,for example, impregnation with chloroplatinic acid normally results inchlorine addition to the catalyst. Halogen may also be incorporatedduring the activation process previously described.

Following incorporation of the porous solid carrier with the platinumgroup component, the tin component, and the halogen, the resultingcomposite is usu ally treated by heating at a temperature of, forexample, no greater than 500F and preferably at 200 to 400F. Thereafterthe composite can be calcined at an elevated temperature as, forexample, up to l,300F., if desired. In the case of sequential depositionof the metal components onto the porous solid carrier, it may bedesirable to dry and calcine the catalyst after the introduction of oneof the metal components and prior to introduction of the other.

Following calcination, the catalyst containing a platinum groupcomponent and a tin component is preferably heated at an elevatedtemperature in a hydrogen containing atmosphere, preferably dry hydrogento produce the catalyst in reduced form. It is particularly preferredthat this treatment with hydrogen be accomplished at a range of 600 tol,300F and preferably from 600 to 1000F. The heating in the presence ofhydrogen preferably continues until the partial pressure of hydrogensubstantially stabilizes. This will usually take 5 minutes or longer.The treatment in the presence of hydrogen should be accomplished in ahydrocarbon-free environment. Thus, any hydrocarbon on the catalystshould be removed prior to contact with the hydrogen. The environmentshould also be substantially free of carbon oxides. By reduced form itis not meant to imply that the entire catalyst or even all of theplatinum group component and tin component are reduced to a zero valencestate, although the great major ity of the platinum group component isbelieved to be reduced to the metal (zero valence). The reduction of thecatalytic composition as described above to form a reduced catalyticcomposition enhances the usefulness of the catalytic composition in, forexample. reforming processes.

The novel catalytic composition of the present invention finds utilityfor various hydrocarbon hydroconversion reactions including hydrofining,hydrogenation, reforming. alkylation, dehydrocyclization, isomerization,and hydrocracking. The catalyst composition of the present invention ismost advantageously used for reforming. The hydrocarbon feeds employedand the reaction conditions used will depend on the particularhydrocarbon hydroconversion process involved and are generally wellknown in the petroleum art. The conditions of temperature. pressure,hydrogen flow rate, and liquid hourly space velocity in the reactionzone can be correlated and adjusted depending on the particularfeedstock utilized, the particular hydrocarbon hydroconversion process,and the products desired. For example, hydrocracking operations aregenerally accomplished at a temperature of from about 450 to 900F and apressure between about 500 to 10,000 psig. Preferably pressures between1200 to 1600 psig are used. The hydrogen flow rate into the reactor ismaintained between lOOO to 20,000 SCF/bbl of feed and preferably in therange 4000 to 10,000 SCF/bbl. The liquid hourly space velocity (LHSV)will generally be in the range of from 0.l to 10 and preferably from 0.3to 5.

As indicated above. the catalyst of the present The is preferablyemployed in reforming. the feedstock desirably used for reforming is alight hydrocarbon oil, e.g., a naphtha fraction. Generally, the naphthawill boil in the range falling within the limits of from 70 to 550F andpreferably from 150 to 450F. The feedstock can be, for example, either astraight-run naphtha or a thermally-cracked or catalytically-crackednaphtha or blends thereof. The feedstock can preferably be low insulfur, i.e., preferably contain less than 10 ppm sulfur and morepreferably less than 5 ppm sulfur. In the case of a feedstock which isnot already low in sulfur, acceptable levels can be reached byhydrogenating the feedstock in a presaturation zone where the naphtha iscontacted with a hydrogenation catalyst which is resistant to sulfurpoisoning. A suitable catalyst for this bydrodesulfurization process is,for example, an aluminacontaining support with a minor proportion ofmolybdenum oxide and cobalt oxide. Hydrodesulfurization is ordinarilyconducted at a temperature of from 700 to 850F, a pressure of from 200to 2000 psig, and a liquid hourly space velocity of from 1 to 5. Thesulfur contained in the naphtha is converted to hydrogen sulfide whichcan be removed prior to reforming by suitable conventional processes.

The feedstock can preferably be low in moisture i.e., preferably containless than 50 ppm water (by weight) and more preferably less than ppmmoisture. This limits the amount of moisture that contacts the catalystand thereby serves to keep the activity of the catalyst high for longerperiods of time.

Reforming conditions will depend in large measure on the feed used,whether highly aromatic, paraffinic or naphthenic, and upon the desiredoctane rating of the product. The temperature in the reforming processwill generally be in the range of about 600 to l l00F and preferablyabout 700 to l050F. The pressure in the reforming reaction zone can beatmospheric or superatmospheric. The pressure will generally lie withinthe range of from 25 to 1000 psig and preferably from about 50 to 750psig. The temperature and pressure can be correlated with the liquidhourly space velocity (LHSV) to favor any particularly desirablereforming reaction as, for example, dehydrocyclization, orisomerization. Generally, the liquid hourly space velocity will be from0.1 to 10, and preferably from I to 5.

Reforming of a naphtha is accomplished by contacting the naphtha atreforming conditions and in the presence of hydrogen with the desiredcatalyst. Reforming generally results in the production of hydrogen. Thehydrogen produced during the reforming process is generally recoveredfrom the reaction products and preferably at least part of said hydrogenis recycled to the reaction zone. Preferably, the recycle hydrogen issubstantially dried, as by being contacted with an adsorbent materialsuch as a molecular sieve, prior to being recycled to the reaction zone.Thus, excess or make-up hydrogen need not necessarily be added to thereforming process, although it is sometimes preferred to introduceexcess hydrogen at some stage of the operation, for example, duringstartup. Hydrogen, either as recycle or make-up hydrogen, can be addedto the feed prior to contact with the catalyst or can be contactedsimultaneously with the introduction of feed to the reaction zone.Generally, during startup of the process, hydrogen is recirculated overthe catalyst prior to contact of the feed with the catalyst. Hydrogen ispreferably introduced into the reforming reaction zone at a rate of fromabout 0.5 to 20 moles of hydrogen per mole of feed. The hydrogen can bein admixture with light gaseous hydrocarbons.

Although, as previously pointed out, it is not necessary, it may bedesirable in some instances to presulfide the catalyst prior to use incatalytic hydroconversion reactions, for example, reforming. Thepresulfiding can be done in situ or ex situ by passing asulfur-containing gas, e.g., H 8, and hydrogen through the catalyst bed.A temperature of from 25 to ll00F or more can be used for thepresulfiding. Other presulfiding treatments are known in the prior art.It may also be desirable on startup of the reforming process to use asmall amount of sulfur, e.g., H S or dimethyl disulfide. The sulfurcompound is added to the reforming zone in the presence of the flowinghydrogen. The sulfur can be introduced into the reaction zone in anyconvenient manner and at any convenient location. It can be contained inthe liquid hydrocarbon feed, the hydrogenrich gas, the recycle liquidstream or a recycle gas stream or any combination.

After a period of operation when the catalyst becomes deactivated by thepresence of carbonaceous deposits, the catalyst can be regenerated, forexample, by passing an oxygen-containing gas having no more than about 2percent oxygen, into contact with the catalyst at an elevatedtemperature in order to burn carbonaceous deposits from the catalyst.The method of regenerating the catalyst will depend on whether there isa fixed bed. moving bed, or fluidized bed operation.

It may be desirable to activate the catalyst after if has beenregenerated by reacting it with an activating gas including oxygen. Theactivating technique is that disclosed above for increasing the activityof a catalyst where tin has been included by an aqueous impregnatingprocedure. It is generally preferred to include a halogenating componentwith the activating gas when activating a deactivated and regeneratedcatalyst. The reason for this is that the deactivated and regeneratedcatalyst may have lost some halogen content during its use in ahydrocarbon hydroconversion process. The catalyst may be analyzed forhalide content to determine whether a halogenating component should beincluded with the activating gas.

After regeneration, or regeneration and activation if the catalyst isactivated, the catalyst is preferably heated at an elevated temperaturein a hydrogen containing atmosphere to reduce it. Preferably the heatingis performed in the presence of a substantially hydrocarbon-free,hydrogen containing gas that is preferably substantially dry at atemperature from 600F. to 1,300F., and more preferably from 600F. to1000F. The substantially hydrocarbon-free hydrogencontaining gas ispreferably also free of carbon oxides and water.

The process of the present invention will be more readily understood byreference to the following Exam ples.

EXAMPLE 1 A catalyst comprising platinum, tin, and chlorine inassociation with alumina was prepared as follows: Stannic tetrachloride(anhydrous) in an amount of 0.5 ml was diluted to 65 mls by the additionof absolute ethanol. The stannic tetrachloride-ethanol solution was thencontacted with 125 grams ofa commercially available 0.3 weight percentplatinum-0.6 weight percent chlorine-alumina catalyst. The impregnatedcomposite was then left for 2 hours in a closed vessel at roomtemperature. Thereafter the composite was dried in a vac uum oven forapproximately 16 hours at about 250F. The catalyst was then calcined inflowing air for about 2 hours at 900F and then reduced in one atmosphereof hydrogen for 1 hour at 900F. The resulting catalyst contained about0.5 weight percent tin and about 1.0 weight percent chlorine.

The catalyst was tested for reforming of a naphtha feed having a boilingrange of 1 to 428F comprising 23.4 volume percent aromatics, 36.5 volumepercent paraffins, and 40.1 volume percent naphthenes. The feed wasessentially sulfur free. Reforming conditions included a pressure of 125psig, a liquid hourly space velocity of 3 and hydrogen to hydrocarbonmole ratio of 3; once-through hydrogen was used. The temperature wasadjusted to maintain conversion to 99 F-l clear octane product.

For comparison purposes, the commercially avail able 0.3 weight percentplatinum-0.6 weight percent chlorine-alumina catalyst was also testedfor reforming at the same reaction conditions and with the same feed asthat described above for the platinum-tin catalyst.

The reforming processes were conducted under con ditions to simulate anaccelerated life test for the cata lyst. These conditions were notnecessarily maintained at levels used in a commercial reforming processbut,

in general, were much more severe to test in a relatively few hours howwell the catalyst would perform. The increase in temperature necessaryto maintain conversion to 99 F-l clear octane product was measured foreach catalyst to give an indication of the activity and temperaturestability of each catalyst. The results are shown in the graph in FIG.I. The change in yield of C gasoline product over the period of the runwas measured for each catalyst to give an indication of the yieldstability of each catalyst. The C gasoline yield product having anoctane rating of 99 F-l clear is shown in FIG. 2.

The response of the platinum-containing catalyst to the simulated lifetest was very poor compared to the performance of the platinum-tincatalyst. As seen in FIG. 1, it was necessary to increase thetemperature very rapidly for the process using the platinum catalystwithout tin in order to maintain a 99 Fl clear octane. Moreover, theyield of C liquid product having the desired octane rating decreasedsignificantly for the process using the platinum catalyst without tin asshown in FIG. 2. On the other hand, the catalyst comprising platinum andtin performed remarkably well during the reforming test. From FIG. 1 itcan be seen that the reforming temperature required to maintain a 99 Flclear octane product increased much slower as compared to thetemperature increase when reforming with the platinum catalyst withouttin. Also, from FIG. 2 the catalyst comprising platinum and tindisplayed remarkable stability during the reforming process. Thus, the Cproduct remained very high during the reforming test compared to the Cyield when reforming with the platinum catalyst without tin. As anotheradvantage of the platinum-tin catalyst, it is noted that the initialstartup temperature for the process using the platinumtin catalyst wassignificantly lower than that of the pro cess using the platinumcatalyst without tin. Also, production of low molecular weighthydrocarbons was low even though the platinum-tin catalyst was notsulfided.

EXAMPLE 2 A catalyst (Catalyst A) comprising 0.3 weight percentplatinum, O.6 weight percent tin, and about 0.9 weight percent chlorinesupported on an alumina car rier was used in reforming a hydrofmed,catalytically cracked naphtha under accelerated conditions. The catalystwas reduced prior to use. The process was conducted at reformingconditions including an average reactor pressure of 125 psig, ahydrogen-tohydrocarbon molar ratio of 3.0 and a liquid hourly spacevelocity of 3. The temperature ofthe catalyst was adjusted throughoutthe run to maintain production of a F-l clear octane product. The runwas made using oncethrough hydrogen. The hydrofined, catalyticallycracked naphtha had an initial boiling boint of 151F, an end boilingpoint of 428F, and a 50 percent boiling point of 307F. The researchoctane number of the feed, without antiknock additives (Fl clear), was64.6. The naphtha contained less than 0.1 ppm nitrogen and less than 0.1ppm sulfur. The feed was specifically chosen because of its severedeactivating effect upon reforming catalysts. Using this feed and theabove reaction conditions, tests of reforming catalysts can beaccelerated, i.e., performed in a fraction of the time needed with aless severely deactivating feed and less severe conditions.

The results of reforming the naphtha at the acceler ated conditionsspecified. using Catalyst A, are shown in FIGS. 3 and 4. The graph inFIG. 3 shows the average catalyst temperature in degrees Farenheit as afunction of the run length. The graph in FIG. 4 shows the C yielddecline as a function of the run length.

A catalyst (Catalyst B) comprising 0.3 weight percent platinum. 0.6weight percent tin, and about L35 weight percent chlorine supported onan alumina carrier was used in reforming the same hydrofined,catalytically cracked naphtha under the same accelerated conditions aswas Catalyst A. Catalyst B was a regener ated and activated catalystthat had previously become deactivated by use in a pilot plant run.

The regeneration of Catalyst B was accomplished by passing a gascomprising nitrogemoxygen, the oxygen being present in about 0.5 volumepercent, through a bed ofthe catalyst at a temperature of 750F. Thetemperature in the bed increased to about 800F as the combustion flametravelled through the bed. The temperature of the bed was then increasedto about 850F and a small amount of additional burning off of cokeoccurred.

The catalyst was contacted with an air-nitrogencarbon tetrachloridemixture having about 5 percent oxygen at a temperature of about 950F toactivate it. The air-nitrogen-carbon tetrachloride mixture containedabout 0.3 percent moisture. The catalyst was then flushed of air.moisture. nitrogen, and carbon tetrachloride, heated in pure dryhydrogen at 900F to reduce it, and then contacted with the feed atreforming conditions.

The results of reforming the naphtha at the conditions specified withCatalyst B are shown in FIGS. 5 and 6. The graph in FIG. 6 shows theaverage catalyst temperature in degrees Farenheit as a function of runlength. The graph in FIG. 6 shows the C yield decline as a function ofrun length.

As can be seen from FIGS. 36, regeneration and activation ofaplatinum-tin-chlorine catalyst results in the restorationofsubstantially the initial activity of the catalyst, i.e., initialcatalyst temperature of Catalyst B was within a few degrees Farenheit ofthe initial catalyst temperature of Catalyst A. It is noted that a runlength of approximately equal time can be obtained after regenerationand activation.

The graphs in FIGS. 4 and 6 show the C,-,+ liquid yield produced duringthe reforming process as a function of run length. It can be seen thatthe yield remained at least about volume percent throughout the runswith both Catalyst A (fresh) and Catalyst B (regenerated and activated).

The foregoing disclosure of this invention is not to be considered aslimiting since many variations can be made by those skilled in the artwithout departing from the scope or spirit of the appended claims. Thus,the catalyst of the present invention can be used for isomerization ofalkyl aromatics, e.g., the isomerization of xylenes to other xyleneisomers.

I claim:

1. A regenerative process for the hydroconversion of hydrocarbons. whichcomprises (1 contacting the hydrocarbons at hydroconversion conditionsin the presence of hydrogen with a catalyst comprising a platinum groupcomponent in an amount from 0.0l to 5 weight percent, a tin component inan amount from 0.01 to 5 weight percent, and a halogen in an amount from(H to 3 weight percent in association with a porous solid carrier. untilsaid catalyst has become deactivated by carbonaceous deposits. and (2]contacting the deactivated catalyst with an activating gas containingoxygen at elevated temperatures for a time sufficient to activate thecatalytic composition.

2. A process as in claim 1 wherein the porous solid carrier is alumina.

3. The process of claim 1, wherein said activating gas also contains ahalogen component.

4. The process of claim 1, wherein the catalyst is reduced in thepresence of hydrogen after contact with said activating gas.

1. A REGENERATIVE PROCESS FOR THE HYDROCONVERSION OF HYDROCARBONS, WHICHCOMPRISES (1) CONTACTING THE HYDROCARBONS AT HYDROCONVERSION CONDITIONSIN THE PRESENCE OF HYDROGEN WITH A CATALYST COMPRISING A PLATINUM GROUPCOMPONENT IN AN AMOUNT FROM 0.01 TO 5 WEIGHT PERCENT, A TIN COMPONENT INAN AMOUNT FROM 0.01 TO 5 WEIGHT PERCENT, AND A HALOGEN IN AN AMOUNT FROM0.01 TO 3 WEIGHT PERCENT IN ASSOCIATION WITH A POROUS SOLID CARRIER,UNTIL SAID CATALYST HAS BECOME DEACTIVATED BY CARBONACEOUS DEPOSITS, AND(2) CONTACTING THE DEACTIVATED CATALYST WITH AN ACTIVATING GASCONTAINING OXYGEN AT ELEVATED TEMPERATURES FOR A TIME SUFFICIENT TOACTIVATE THE CATALYTIC COMPOSITION.
 2. A process as in claim 1 whereinthe porous solid carrier is alumina.
 3. The process of claim 1, whereinsaid activating gas also contains a halogen component.
 4. The process ofclaim 1, wherein the catalyst is reduced in the presence of hydrogenafter contact with said activating gas.